Prime Minister John Key and his Samoan counterpart have signed a double-tax agreement in Samoa.
The announcement comes on the day of the All Blacks' first test match on Samoan soil.
The double-tax agreement will help reduce tax barriers to two-way trade and investment by preventing cross-border income being taxed twice.
Mr Key said it would help further trade relationships between the two countries and acknowledged it would be particularly beneficial for Samoa.
"New Zealand is Samoa's second largest trading partner. The agreement will provide a platform for increased trade and investment between our two countries - and will help assist the economic development of our Pacific Island neighbour."
The new tax agreement will come into play later this year.